Split ring fasteners have long been used to secure telescopically related parts, i.e., parts having concentric circular surfaces disposed one within the other. Most frequently, the split ring is seated in a transverse annular groove and has an active face which lies in a plane at right angles to the central axis of the telescopically related surfaces and is exposed for axial engagement by, e.g., a transverse annular shoulder on the part to be secured. In such cases, the split ring may be thin, and may have a relaxed diameter different than that of its retaining groove, so that the ring is resiliently distorted in a sense forcing the ring into engagement in the groove. A common example is use of a split ring to secure a pulley on its shaft. With advance of the arts, cases have occurred in which the space available to accommodate such fastener rings is small, and prior-art workers have proposed to cant the ring so that, when installed, the active face or faces of the ring lie as frustoconical surfaces tapering toward the retaining groove. Thus, as seen in French Pat. No. 1,124,542, published Oct. 12, 1956, the split ring is a thin normally flat resilient ring which, when installed, is distorted into frustoconical form, with the spring force of the distorted ring urging one frustoconical face of the ring into engagement with an annular rounded edge on the part to be secured. Similarly, a relatively thin normally frustoconical split ring fastener is disclosed in U.S. Pat. No. 3,413,022, issued Nov. 26, 1968, to R. F. Waddell, one frustoconical face of the ring being in flush engagement with a frustoconical shoulder when the ring has been installed, the other frustoconical face of the ring engaging an annular corner presented by the retaining groove.
Such prior-art inventions have achieved success and acceptance for applications in which the split ring is required to transfer only relatively small forces. However, for applications where very large forces must be transferred from one part to another via the fastener ring, as in the case of well tools and the like, there has been a continuing need for improvement.